1. Field of the Invention
The present invention relates to an air-core stepping motor using a hollow rotor. More particularly, the invention relates to an air-core stepping motor having a novel shaft support structure.
2. Description of the Related Art
The present inventor has proposed a method of supporting a rotor rotatably with respect to a stator in an air-core stepping motor by arranging a plurality of shafts, extending in the axial direction, along the outer periphery of the stator, and a plurality of rollers rotatably fitted to the shafts, and causing the rollers to roll in contact with the outer surface of the rotor to thereby support the rotor (see JP-A-2006-211919 (Patent Document 1)). This method is cheaper than commercially available bearings, and can make the air-core stepping motor lighter. Further, the method has an advantage such that the shafts if provided with radial elasticity can absorb run-out and make the rotation of the rotor smoother.